1. Field of the Invention
This invention deals with an extrudable plastic drywall corner strip, commonly called a corner bead, suitable for reinforcing corners of arches. The exposed surfaces of the strip having a finish suitable to allow joint compound to adhere to it.
2. Description of Related Art
Metal corner beads have been in use for a long time in the drywall application industry. Generally, these beads are formed from tin by taking a long tin strip and bending it longitudinally along its center to form a hollow raised bead and two straight legs. The inside angle of such a bead is generally just under 90.degree..
In order to form an arch, having either an outside or inside curve without buckling and kinking, slits are cut with tin snips repeatedly in one of the flat legs. The corner formed by such a modified tin bead is unsatisfactory because the hollow bead tends to kink or tear, creating an angular effect, with alternating kinks and flat spots. In order to prevent this kinking, the slits can be cut so that they do not reach the bead. This, however, is still unsatisfactory, because the tin tends to tear along shear lines created by stress when trying to force the bead around a curve. Using ordinary tin snips for cutting slits causes the metal to curl, resulting in a poor uneven surface for applying joint compound. Tin strips are also difficult to nail to the drywall because the final hammer blows cause permanent deformation.
Plastic strips containing a hollow head are commercially available. Although these strips are more efficacious in forming nailable tabs when slits are cut, the hollow raised bead does not address the problems of kinking and tearing when force is applied to form arches.
It would be desirable, therefore, to have strips made from some type of resilient material, which will not permanently deform when suffering a blow, which is flexible but sufficiently tensile to form a smooth curve, and which is textured so as to hold a joint compound applied to the corners.